Simulation and understanding of the major transitions in Quaternary climate dynamics
Geophysics
Final Report Abstract
Understanding climate variability during the past 3 million years remains a scientific challenge. Paleoclimate records provide rich information about Quaternary climate cycles but the mechanisms of these transitions are still not properly understood. In the framework of this project we performed first simulations of Quaternary glacial cycles with a comprehensive Earth system model driven by orbital forcing only. We than performed a systematic testing of different hypothesis proposed to explain Quaternary climate variability and pronounced regime changes. To this end we further developed existing CLIMBER-2 model and used a novel time-splitting approach to perform a large set of 3-million years-long simulations with interactive ice sheet and carbon cycle component. We demonstrated that Pliocene-Pleistocene Transition (ca. 2.7 Ma) and the onset of Northern Hemisphere glaciation can be explained by a gradual reduction in atmospheric CO2 concentration. At the same time, we found that the Mid-Pliocene Revolution (between 1.2 and 0.8 Ma), which is the transition between 40-kyr and 100-kyr worlds, can be explained by a gradual removal of regolith by ice sheet over North America. The weak dependence of simulated glacial cycles on initial conditions strongly suggests that glacial cycles are externally forced and mostly deterministic. In the framework of the project we undertook significant effort on development of new CLIMBER-3ice model which will be used instead of CLIMBER-2 in our future research. Results of this project also contributed to the progress in understanding the non-linear dynamics of the principal components of the Earth system, such as ice sheets, ocean circulation and carbon cycle, as well as the role of various climate feedbacks.
Publications
- 2017: The importance of snow albedo for ice sheet evolution over the last glacial cycle
Willeit, M., Ganopolski, A.
(See online at https://dx.doi.org/10.5194/cp-2017-122) - 2015: Coupled Northern Hemisphere permafrost-ice-sheet evolution over the last glacial cycle, Climate of the Past, 11(9), 1165–1180
Willeit, M. and Ganopolski, A.
(See online at https://doi.org/10.5194/cp-11-1165-2015) - 2015: The role of CO2 decline for the onset of Northern Hemisphere glaciation, Quaternary Science Reviews, 119, 22–34
Willeit, M., Ganopolski, A., Calov, R., Robinson, A. and Maslin, M.
(See online at https://doi.org/10.1016/j.quascirev.2015.04.015) - 2016: PALADYN v1.0, a comprehensive land surface–vegetation–carbon cycle model of intermediate complexity, Geosci. Modeling Development, 9, 3817-3857
Willeit, M. and Ganopolski, A.
(See online at https://doi.org/10.5194/gmd-9-3817-2016) - 2017: Simulation of climate, ice sheets and CO2 evolution during the last four glacial cycles with an Earth system model of intermediate complexity. Climate of the Past, 13, 1695–1716
Ganopolski, A., Brovkin, V.
(See online at https://doi.org/10.5194/cp-13-1695-2017)
